Keychron and System76 are also on the QMK train with their recent keyboards too. (I'm not 100%, would love to know if each of these can be flashed by users.)
Framework is also on the QMK open-source firmware train, for their keyboard + trackpad combo. Also not a new trend for them: their newer laptops I believe all run Zephyr OS for the embedded controller (EC), & are themselves open source too. Before that, the open-source Chromebook EC. I believe it's possible to compile - flash your own. https://frame.work/blog/previewing-the-framework-wireless-to... https://github.com/FrameworkComputer/EmbeddedController/tree...
These companies are both loved, in ways very very few companies are. It's obvious why.